Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

762
FXUS63 KLOT 302353
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
553 PM CST Fri Jan 30 2026

.KEY MESSAGES...

- Lake effect snow will continue to result in hazardous travel
  across parts of northeastern IL early this evening before the
  main focus for lake effect shifts into northwestern IN later
  this evening and overnight.

- Significant snowfall accumulations and dangerous travel expect
  near the lake in northwest Indiana tonight into Saturday.

- Lake effect snow will return to parts of far northeastern IL
  on Saturday. This is likely to result in some additional
  localized accumulations and potential travel impacts on
  Saturday in parts of Cook and eastern Will counties east of
  I-57.

- There may be a period of light snow accumulations Sunday
  night into Monday, followed by less cold conditions by
  midweek.

&&

.DISCUSSION...
Issued at 323 PM CST Fri Jan 30 2026

Headlines...

Headlines are a mess, owing to the expected behavior of the lake
effect band tonight through Saturday. Overall, the band of
impactful snowfall looks to move east into northwestern IN tonight,
then shift back west into parts of northeastern IL on Saturday. As
such, we have multiple headlines in effect for portions of
northeastern IL through Saturday. First, a Winter Storm Warning
remains is in effect for much of Cook through this evening, with a
Winter Weather Advisory covering Lake IL, DuPage (and far
northern Cook) into early this evening. Then, with the
expectation of the snow returning on Saturday, we have opted to
go ahead and issue a second Winter Weather Advisory for all Cook
County zones and eastern Will to cover much of the day
Saturday. Otherwise, we continue the Winter Storm Warning
tonight and on Saturday for Lake (IN) and Porter, only pushing
off the start time a few hours.

Tonight through Saturday...

Lake effect snow showers have been impacting much of northeastern
IL today, with the most intense snow showers as of this writing
falling just inland of the lake from Chicago northward. Expect
this activity to persist through late this afternoon, with
localized snow rates of 1 to 2 inches. As we head into this
evening the broader synoptic flow will back as the mid-level
trough overhead sags to our south. This should foster a transition
in the lake effect character from the ongoing multiple banded
behavior, into a single dominant band of intense snow, with snow
rates possible peaking in excess of 2" per hour. In fact, this
behavior has been noted for several hours today across central
parts of the lake.

It appears this intense band of lake effect snow will quickly
shift southward down the northeastern IL shore after 6 PM this
evening, before settling somewhere across southern Lake Michigan
near, or just east of the Illinois and Indiana state line mid to
late this evening. This thus looks to put parts of Lake County IN
and adjacent areas of western Porter (and perhaps far
southeastern Cook) in the target zone for periods of intense lake
effect snow through the evening. With snow rates of 2"+ per hour,
near white out conditions are likely at times, which will result
in a period of dangerous travel tonight from near the IL and IN
state line eastward along the I-80, I-90 and I-94 corridors right
across Lake and into Porter counties in IN.

This lake effect band is likely to wobble, and/or shift eastward
a bit overnight as a series of meso-lows track southward and crash
onshore across southern Lake Michigan into northwestern IN.
Accordingly, some periodic breaks in the heavier snow are likely
across parts of Lake IN County overnight, (with the snow likely
stopping all together across northeastern IL overnight) as the
main focus (at least temporarily) shifts into Porter County. Lake
induced inversion heights are expected to gradually lower late
tonight into Saturday morning. However, the presence of strong
boundary layer convergence is expected to persist on the lake, and
will thus continue to support some heavier rates of snow within
the main band into Saturday morning.

The forecast consensus continues to favor the focus for this band
of lake effect snow to shift back westward towards the
northeastern IL shore Saturday morning. We thus should see
accumulating snow return to parts of northeastern IL on Saturday,
and it could persist for several hours into Saturday afternoon
before weakening into Saturday evening. While some occasional
heavy rates may persist within the lake effect band on Saturday,
favorable thermodynamics on the lake will continue to fade with
lowering inversion heights through the afternoon. This should thus
result in a lower footprint of the heavier rates of snow as the
band moves into northeast IL on Saturday. Nevertheless, some
localized additional accumulations could exceed 3".

KJB


Saturday Night through Thursday:

Active northwest flow will continue beyond this weekend`s
system and into next week, and will guide several disturbances
across the general region through next week. Medium range
guidance continues to resolve the first of these waves scooting
across the Upper Midwest and Great Lakes region sometime during
the Sunday PM - Monday timeframe. In general, large scale height
falls don`t appear all that impressive, with the main surface
trough and associated low forecast to slide well to our north.
However. fairly robust DCVA on the southern flanks of this
feature, coupled with north-south transient bands of mid-level
f-gen may be sufficient to crank out some light snowfall over
parts of the area, particularly the closer to the Wisconsin
state line you get. The fairly quick forward progression of this
system, as well as a general lack of deeper moisture, suggests
snowfall amounts will be light, probably limited to a few tenths
to an an inch or so. Based on the latest guidance trends, it`s
possible dry air plays a role and ultimately limits snowfall
chances with this feature as well.

Deterministic and ensemble guidance spread increases markedly
after Tuesday, lowering overall forecast confidence during the
middle and end of next week. With a lingering baroclinic zone
just to our south, there`s a potential for some continued
precipitation chances even into Tuesday/Wednesday, but this is
far from ubiquitous across the guidance suite.

While below normal temperatures are expected to continue into
early next week, there` a decent model signal for at least a
moderating trend during the middle and end of the week, with
highs potentially pushing near and above freezing.

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 553 PM CST Fri Jan 30 2026

Forecast concerns for the terminals...

- Band of heavy lake effect snow will persist through tonight in
  northwest IN resulting in LIFR visibilities.

- Lake effect wobble back west towards the Chicago terminals
  Saturday morning, but uncertainty remains on how far west the
  band gets and its intensity.

- VFR conditions expected outside of lake effect.


The initial band of lake enhanced snow is progressing
southwestward across north-central IL resulting in brief periods
of IFR visibilities. This band should begin to wane over the
next 1-2 hours. However, the main lake effect band is developing
over eastern Lake Michigan and will pivot across the Chicago
terminals through 02z this evening. Beneath the band a 1-2 hour period
of LIFR visibilities (as low as 1/2SM) and MVFR ceilings is
expected in addition to a quick 0.5 to 1 inch of snow
accumulation. As this band pivots into northwest IN by 03z this
evening it is expected to slow and result in a more prolonged
period of LIFR visibilities and IFR ceilings at GYY and points
east. While the exact duration of the band at any one location
remains uncertain, the band is expected to remain over portions
of northwest IN through the night and will be wobbling between
VPZ and GYY during this time. Where the band remains the longest
will likely see accumulations upwards of 6 inches with locally
higher amounts possible.

Heading into Saturday morning, the lake effect band is forecast
to begin to swing back west towards the Chicago terminals.
Despite the decent agreement in guidance on this scenario, there
remains a fair bit of uncertainty as to how far west the band
will get and its intensity. Therefore, have opted to maintain
the PROB30s at ORD, MDW, and GYY but did opt to introduce a
prevailing group of flurries at ORD and MDW to tease a slightly
earlier arrival. Regardless, where the band does get to another
period of IFR to LIFR visibilities can be expected. The band
will gradually begin to shift back east Saturday afternoon and
should weaken as it does so before finally dissipating Saturday
evening. In terms of accumulation, another burst of 1-3 inches
of snow is possible especially where the band sits the longest.

Outside of the lake effect, expect VFR conditions to prevail
through the forecast period. Winds will also be northwest around
7-10 kts through the period, but instances of northeast winds
are possible under the main lake effect band.

Yack

&&

.HYDROLOGY...
Issued at 230 PM CST Wed Jan 28 2026

River gauges, reports from local officials, and reports from
trained ice spotters continue to indicate a few ice jams across
the area due to the significant increase in river ice over
recent days. With continued cold weather into next week,
conditions will remain favorable for river ice formation. While
no widespread flooding is expected, localized ice jams may
occur.

- NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Weather Advisory until 8 PM CST this evening for ILZ006-
     ILZ013-ILZ103.

     Winter Storm Warning until midnight CST tonight for ILZ104-
     ILZ105.

     Winter Weather Advisory from 6 AM to 4 PM CST Saturday for
     ILZ103-ILZ104-ILZ105-ILZ108.

     Winter Weather Advisory until midnight CST tonight for ILZ108.

IN...Winter Storm Warning until 6 PM CST Saturday for INZ001-INZ002.

LM...Small Craft Advisory until 2 PM CST Saturday for the IL and IN
     nearshore waters.

&&

$$

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